The present invention relates to portable computers, such as those commonly referred to as laptop or notebook computers; and specifically to data input devices for use with portable computers and means for protecting such input devices while transporting the computer.
Computers have evolved from room-sized apparatus to desktop personal computers and then to devices which have a size similar to a three-ring notebook. In reducing the computer to a portable size, certain input devices commonly associated with larger computer systems were combined in order to provide a more compact device. For example, desktop computers often had a trackball mechanism that the user manipulated to move a cursor on the display screen of the personal computer or terminal. A track ball has a sphere which is rolled in a socket by the fingers of a user and which engages a pair of wheels which rotate as the sphere is manipulated. The wheels are coupled to a potentiometer having a resistance that varies with the movement of the ball. The axes of the wheels are perpendicular to each other so that the potentiometers produce signals representing movement in two dimensions. These signals are used to position a cursor on the display screen. In some trackballs, slotted wheels are driven by the movement of the sphere and interrupt a beam of light in an electro-optic device, which produces a pulsed electrical signal that is used to position a cursor. Similarly, the numeric keypad usually found on full size desktop keyboards was eliminated from many portable computer keyboards to save space. As a result, standalone keypads are available as after market input peripherals.
Another input mechanism includes a transparent conductive coating on the outer surface of the display screen. The user touches the display screen with an electrically conductive stylus to indicate a particular position on the display screen. The stylus coming into contact with the surface of the display screen alters an electrical characteristic of the coating, enabling the point of contact to be sensed by detection circuitry. An example of this type of input mechanism is described in U.S. Pat. No. 4,129,747. Similar stylus devices have been used with a flat horizontal tablet onto which the user can enter graphical or handwritten information which is stored as an image in the computer system.
In addition to combining certain components in the course of designing portable computers, those components were densely packaged into as small a case as possible. The case itself was made as light as possible to facilitate portability. These factors make the components of the computer susceptible to damage when the case is dropped or jarred forcibly. Portable computers commonly are carried in cushioned bags which offer some degree of additional protection. However, such bags increase the bulk of the package being carried as well as creating a separate item which must be stored when the computer is being used. It is therefore desirable to provide elements which increase the resistance of the computer to damage while remaining integrated with the basic case.
The reduced size of the portable computer often produced discomfort for the user's hands and wrists while using the keyboard. This led to a need to provide a rest for the hands of the operator at the same level as the top of the keyboard. Placing a separate rest in front of the keyboard or moving the keyboard backward on the computer case has addressed this need.